Weft-straightening apparatus



A ril 24, 1956 J- D. ROBERTSON WEFT-STRAIGHTENING APPARATUS 3 Sheets-Sheet 1 Filed Feb. 8, 1952 April 24, 1956 J. D. ROBERTSON 2,742,635

wEFT-STRAIGHTENING APPARATUS Filed F 8 19 52 I t 3 Sheets-Sheet 2 v 2,742,685 WEFT-STRAiGHTENIN G' APPARATUS John D. Robertson, 'Iiaunton, Mass. Application February 8, 1952, Serial No. 270,569 11 Claims. cerea -63 I :lhis invention relates to improvements in weft-straightemng apparatus of the "general type wherein skewed and/or bowed weft or filler elements of a travelling web of woven cloth, or the like, rightangular relation totlie warp elements of the web byrequ ring some of the warp elements to travel through longer paths than others in going froin one transverse gu de member to a another generally parallel transverse guide member. The invention provides. improvements in such weft straight'eners whereby the weft-straightening action of a weft-straightening roll on a travelling webis such that the tensioninthe portion of the web being drawn from the weft-straightening, apparatus into a 'tenter frame, for example, is not substantially'incr'eased due to the Weft-straightening process and is more uniformly distributed among the warp elements of the web as com United States Patent may be resto'red toftheir proper pared with webs acted'upon'by the prior weft-straighten- 1 ing devices. t V in the textile indusn woven fabrics are subjected to various treatments after being woven. Initially the Weft or filler elements are perpendicular to'the warp elements.

However, in the course of'sub's'eque'nt processing, the weft or filler elements frequently become skewed and/or bowed relative to the warp elements. They may become displaced into a skewed condition "in which their ends at one selvag'e of the Web may lead or lag behind their ends at the other selvage, or they may become bowed with their central portions either leading or lagging behind their-ends at the two selvages of the web. Sometimes the weft or filler elements acquire a combination bow and skew. Regardless of what partieular displaced relationship the weft or filler elements may have in 'a travelling web; it becomes necessary or desirable to restore the weft or filler elements to proper peipendicularity to the warp elements before the vweb passes from a weft-straighte ening apparatus into a tenter frame or'other processing mechanism; Straightening of the weft or filler elements of a web preferably willbe' accomplished while the web is in a moist condition, and the web then is'dried to set its weft and warp elements in their proper rig'ht angnlar relationships. Customari ly, a web passes from a weftstraig'htening apparatus to a tenter frame which grips the opposite selvages and holds the web to a desired width during the drying process. 1

Various devices have been 'proposedhere'tofore for correcting skew and bow of the weft or filler elements of travelling webs. The more satisfactory varieties have employed tiltable and/ or curvedrolls' which engage the travelling'w'eb and which have been capable, when properly positioned, of increasinge decreasing the length of the paths of travel, between two spaced and'parallel transverse guide elements, of particular warp elements of a travelling web relative to the length of the paths'of travel of other warp elementsof'the web. Of course, the object has been to enable portions of wait "or filler elements-of the web which maybe lagging behind other portions of the same weft or filler elements to move abreast of the leading .portionswhile thelatter portions I atented Apr. 24, 1956 ice tortin'g tension in the portion of the web leaving the weftv straightening apparatus, and the distorting tension frequently counteracts and nullifies the intended weftstraightening action of the rolls, or the rolls may produce an uncontrollable over correction. Forexample, assum= ing that a web is being drawn through a bow correcting weft-straightener by a tenter' frame whose clips grip the opposite selvages of the web, both selvages will be advanced at a substantially uniform rate. Inasmuch-as the draft of the web has been relied upon to rotate the prior weft-straightening rolls, any weft-straightening actionof a roll on the web necessarily introdu'ees substantially increased tensionin those warp elements of the web which are made to travel longer paths'than other warp elements. In the assumed case of a curved roll weftstraightener, and assuming bow of the weft or filler threads with their central portions leading their ends, the central warp threads will be made to travel longer paths than the warp elements at and near the opposite selvages of the web. These central elements are required to travel over the elevated crest of the curved expander roll and are subjected to substantially increased tension while warp elements at and near the selvages have less tension. Hence, these tensioned central warp elements initially assome the major portion of the burden of rotating the curved roll, and warp elements outward from the center toward the selvages have varying degrees of slacknes's around the roll. In other words, the friction between the web and the roll, necessary for rotating the roll, is concentrated at the central portion of the web and the resistance offered by the roll to being rotated has the effect of holding back the tensioned central warp elements while selvage regions of the web are relatively free to be drawn forward; The ends of the weft or filler elements quickly overtake the previously leading central portions of those elements and the elements may become bowed in the opposite direction before the actionv of the roll on the web can be changed, In any event, the concentration of increased tension on a relatively few warp elements tends to upset the intended corrective action of .the weftstraightening roll on the web.

Generally similar effects have resulted from use of prior tiltable roll weft-straighteners in that the warp elements at that selvage region of a travelling web which is made to travel a longer path than the other selvage region,

strain of rotating the Weft-straightening. roll or rolls.

1 have found that, by driving the roll or rolls with a controllable torque, a tiltable and/ or curved roll may act on a web to effect straightening of skewed and/or bowed weft or filler elements without subjecting any of the warp elements to substantially increased tension'and, as compared to the prior devices, with amore vuniform distribution of the web tension across the full width of the web at that area of the web between the weft-straightening apparatus and the tenter frame, or other web-drawing mechanism. 7

It is, therefore, an object of my present invention to provide a weftstraightening apparatus wherein a weftstraightening roll is operable to straighten skewed and/ or bowed weft or filler elements of a travelling web Without substantially increasing tension in that area'of the web between the weft-straightening roll and a tenter frame, or other web-drawing mechanism. According to the invention, the weft-straightening roll is power driven and its torque is selectively variable to avoid imposition of substantially increased tension on the web due to the action of the roll on the web.

It is, moreover, my purpose and object generally to improve the structure and effectiveness of apparatus for correcting skew and/ or bow of the weft or filler elements of travelling webs without introducing disturbing inequalities of tension distribution across the width of the web at that portion thereof which is leaving the weft-straightening apparatus.

In the accompanying drawings:

Fig. l is a diagrammatic representation of a travelling woven web engaging over a longitudinally curved roll from which the web is advancing, in the direction of the arrows, to a tenter frame, or other processing machine, which draws the web over the curved roll;

Fig. 2 is a top plan view of the apparatus of Fig. 1 but showing the curved roll in its neutral position;

Fig. 3 is a top plan view of one end portion of the curved roll of Figs. 1 and 2, on a larger scale, illustrating the roll as having a non-round axle on which a flexible surface sleeve is rotatably mounted, the end of the axle being secured adjustably in a clamp, and an electric motor being mounted on the axle with drive connection to the rotatable surface sleeve of the roll;

Fig. 4 is a cross-sectional View on line 44 of Fig. 3;

Fig. 5 is a cross-sectional view, on a still larger scale, showing the interior structure of a so-called dry type of curved roll;

. Fig. 6 is an end view of the roll of Fig. 5, the axle being in cross-section;

Fig. 7 illustrates one end portion of a curved roll whose longitudinally curved axle has its end clamped to a pivoted bracket which may be adjusted about its pivot to set the curved axis of the axle in different planes, an electric motor having gear connection to the pivoted bracket for effecting the said adjustments, and an electric motor being shown mounted on one of the gears, with drive connection to the rotatable surface sleeve of the roll;

Fig. 8 is an end elevation of the apparatus of Fig. 7.

Fig. 9 is a cross-sectional view on line 99 of Fig. 8.

Fig. 10 is a diagrammatic showing of the effect on the web of adjusting the curved roll axle to set its axis in different planes, the illustrated roll having a fixed axis of swinging, as in the embodiment of Figs. 7-9; and

Fig. 11 is a diagrammatic representation of a tiltable skew-correcting roll in operative relation to a traveling web and having means for driving the roll and for selectively varying the driving torque.

Referring to the drawings, Figs. 1 and 2 illustrate, diagrammatically, a woven web 10 travelling in the direction of the arrows on a course leading to a tenter frame 12, or the like, the tenter frame drawing the web on its course in guided engagement with guide rolls 14, 16 and 18, with a conventional tension means indicated generally at 20. Between the guide rolls 14, 16, a conventional longitudinally curved roll 22 is shown engaging the web 10, and roll 22 ordinarily will be adjustably mounted so that its curved axis may be set in any of a variety of planes, thereby to vary its effect on the web 10 in a well known manner. It is represented in Fig. l in the position wherein it has maximum bow-correcting effect on weft or filler elements of the web whose central portions are in advance of their end portions. Fig. 2 shows roll 22 swung clockwise through 90 from its position of Fig. 1, to better show its longitudinal curvature.

As best seen in Fig. 5, the curved roll 22 may be of a known type wherein a flexible surface sleeve 24 of rubber. or the like, is rotatable about a longitudinally curved axle 26 whose opposite ends are adjustably secured in suitable clamps, such as the one represented at 28 in Fig. 3.

Heretofore, the travelling web 10 has been required 4 to rotate the flexible surface sleeve 24 of the curved roll 22 and this has had the effect of introducing objectionable and uncontrollable amounts of tension in the web 10 between the roll 22 and the tenter frame 12, or other webdrawing means.

According to my present invention, the flexible surface sleeve 24 of roll 22 is power driven independently of the pull or draft of the travelling web 10. Fig. 5 shows an end portion of a curved roll 22 of a so-called dry type wherein the flexible surface sleeve 24 is directly mounted on a mutiplicity of generally cylindrical metallic roll sections or spools 30 which are arranged in spaced relation along the curved axle 26, each roll section or spool 30 being mounted on and rotatable with the outer ball race 32' of a ball-bearing unit 32 whose inner race 32" is keyed against rotation on the axle 26. Spacing elements 34 loosely surround the axle and are clamped endwise between the inner races of adjacent ball-bearing units 32, whereby the roll sections or spools 30 and the ball-bearing units 32 are maintained in their said spaced relation.

At each end portion of the roll of Figs. 5 and 6, a collar 36 is secured to axle 26 as by one or more set screws 38, these collars 36 engaging the endmost ball-bearing units and maintaining the interior elements of the roll in their proper relationships.

A pulley 40 is secured directly to the flange of the endmost roll section or spool 30, as by the bolts 42, each end of the roll preferably being equipped with a pulley 40, so that the flexible surface sleeve 24 of the roll may be belt-driven by any suitable power means such as two electric motors, one of which is shown at 52 in Figs. 3 and 4 supported on the axle 26 of a roll 22. In some cases, a single motor 52 at only one end of the roll may be found sufiicient but I presently prefer to provide a power drive for each end of the surface sleeve 24. A relatively small pulley 54 on each motor shaft has a belt 56 trained over it and over a pulley 40 on roll 22. Hence, as the axle 26 is adjusted to set its curved axis in different planes, the motor 52 moves with it to maintain the belt 56 always in driving connection with roll 22.

When a roll 22 of the Figs. 5 and 6 form has the opposite ends of its axle 26 mounted in clamps, such as the clamp 28 of Fig. 3, any adjustment of the roll must be effected manually by loosening the clamps and setting the roll in a desired position, followed by tightening of the clamps to maintain the roll in the selected position. It may be set in a neutral position in which all portions of the web across its width will have equal lengths of paths of travel between the guide rolls 14, 16, or it may be set in various positions to variously increase or decrease the paths of travel of the selvages of the web relative to the path of travel of the central portion of the web. And. in any or all of its said positions, the flexible surface sleeve 24 of the roll may be rotated by associated power means which relieves the web of the need for rotating it and of the disturbing tension effects which, heretofore, have resulted when the web was relied upon to rotate the flexible sleeve.

The electric motors 52 which drive the surface sleeve 24 of the roll preferably will be of an available type having the characteristic that its torque does not increase appreciably when it is slowed down by an increase of load. In other words, the motor torque preferably will increase with increase of motor speed only enough to compenstate for frictional losses within the roll, and may be controlled by any suitable rheostat, variable choke or transformer, of which a simple rheostat is represented at 53 in Fig. ll. The control means may be manually operable or automatically responsive to changes in the motor speed, and motors at the opposite ends of a roll will be controlled for synchronized operation.

When it may be desired to automatically adjust a roll 22 in response to bow detecting means, one or more of the rolls may be mounted with the opposite ends of the roll axle or axles clamped to pivoted members which may be swung on their in io'ts to' var y"the'position brpesi tiens' er the roll or 'rolls' Figs. 7:9 illustrate such a mounting for o e endmfa single roll 22, it being assumed that the opposite end of the. roll will be similarly mounted. The endof axle 26 is secured in a clamp 58 which in turn isse'curetl to abracket 60 which isp ivotally mounted at 62 on a support 64. The pivot sha'ft filhasfixed toits inner end the large gear segment through/a hole 67 in which the axle extends. Segment 66 meshes with a pinion 68 on a shaft 70 which has another gear 72 fixed thereon meshing with a'p'inion gear 74 on the shaft of a reversible'motor 76. The'shaft'7 0 extends to the other end'of the tell where a inien'gea 68 (not shown); o the .shaft meshes with a segment 66 (not shown) on apivot shaft 62- (not shown). In other words,'the mechanism'shown in Fig. 7 is reproduced at the 'otherend of the roll excepting the reversible mot'or audits gear connectionlt'o shaft 70, so that o eration of motor 76 in one direction rocks roll 22 in. clockwise direction about the axis of pivot shaft 62, and operation-of motor '76 in the opposite direction rocks roll 2 2 in'counteiclockwise direction about the axis of pivot shaft 6 2. "This mounting for a roll =22 and theautomatic' adjustment of the roll is more particu; larly described'in my Patent No. 2,496,312, issued February 7, 1950, wherein two of the longitudinally curved rolls are shown. t The roll 22 of the Pigs. 7-9 embodiment is belt driven by a variable speed geared motor'52,at each end of the roll, which is shown mounted on the gear segment 66. If desired, the motor may-be-monnted-on theaxle 26 as in tlie'Figs.'3 and 4 embodiment. in either case, the motor moves with the axle during adjustments of the roll.

Curved rolls 22 are suitablefor laterally expanding or contracting a web 10, as well as forcorrecting'bow of the transverse elements of the web.

Al para'tus for corr ting skew-'-:of the transverse elenierits'of a travelling Woven web o'rdinarilyincludesa roll' pivotally supported and adapted to be, tilted to increase the path of travel of one edge of the web relative: to the path of travel of the other edge. Fig. it illustrates a the tension bf the web between therenana th'e'tenter'.

fram'efthu's ensuring a proper drawing and processing effect on the web by the combined action "of the roll and the tenter frame, or other drawing and processing niechani'srn, I i

it is intended that the patent shall cover, by suitable expression in the appended claims, whatever features of patentable novelty exist in the invention disclosed. :iclaim as my invention: l

1. In aweb-handlingapparatus having a pair of spaced and parallel guide elements and web' 'drawing means for. drawing the web in guided engagement with said guide elements, "the combination therewith of a roll disposed transversely of'the web between said guide elements and i'otatably-mounted with its surface engaging the full'width bf the web, means on an end portion of said roll operable for'frn'oving the said roll about an axis different fromthe a set its said rotationthereby to'change theleng th 'of' the path of travel between said guide elementsof one edge of said web relative to a laterally ditferentgportion of the web,and'web-tension-controlling power means conn ected to said roll for 'd rivin'gsaidroll at a selected uniform speed in its diiferen't positions "with a selectively variable torque.

2. In a web-handling apparatus having a pair of spaced and parallel guide elements and web-drawing meansfor v drawing the web in guidedlengagement with said guide eie'merits, the combination therewith'l'of "a roll disposed I transversely of the web between said guide elements and ro'tatably mounted with its surface engaging the run Width of the web, means for shifting said roll betweeir a neutral position, in which all portions across the width 'of the web have equal ien'gth of :paths'o'f travel between skew-correcting mechanism whose tiltable roll .78 .isrotatably mounted in alframe 80 which-frame ;'i"s pivotally mounted at 82 centrally between its eridsfso thatthe frame may be tilted in eitherdirection about-its pivot 82 to correct skew in-a manner which is more particularly described in Patent No. 2,343,328, granted March 7, 1944,: to the present applicant jointly with Joseph L. 'Dub'e. The

'tiltable' roll shaft 79' projects beyondthe'frame'fiil andfit is essential that the roll and. shaft rotate in unison. A

pulley9 4 is fixed on the projecting endof shaft'7-9, and .a motor 52, similar to that of Figs'.,3 and 4, is mounted on the frame 80 with blt-driveconnectionto the pulley' fl i. A single motor 52 with belt-drive connectionto en end of the roll shaft 79 ordinarily will be suflicient. 'However;

if desired, twosynchronized finotor's may drive oppvosite said guide elements, and positions in which an edge portinnof'the web has a length of path of travel 'between said guide elements different from theilength of path of travel of a laterally different portion of the Web means v engaging an end portion of said roll'for driving -said roll in its different'positions, and means for selectively vary- ;-'rneans-thereby to control the tension increasing elfect of I said ro'llon the web.

ing the torque applied to said roll by the said driving g 3. In a web handling' apparatus having'a pair of'sp'ac ejd and parallel guide elements and'web drawing 'means' fo r V drawing the web in guided engagement with said guide elements, the combination therewith of iaflon gitudinally curved roll disposed t'ransverselyof the web between said ends of shaft79,"or"a single motor at oneendhmay have a suitable 'drive'means 'extended'to the opposite end, with belt-drive connection to a pulley 94 at each end of shaft 79. 1

The tiltable roll 7 8 may be an ordinary straight roll,,and the described 'pr ojectin'g endsofshaft 79 obviously maybe there trunnions at the opposite ends ofthe'roll. i

It will be apparent from the-foregoing 'de'scriptiongfthat either a longitudinally curved roll or a tiltablefroll may be, acting on the travelling web. 10 in a mannefi t o'c'orrect skew and/or bow of the weft or 'fille'r elements of, the.

web, and that the invention provides mean's'forlselectiye'l'y driving the weft-straightening roll: so [as to control guide elements, said rollhaving a longitudinally curved I 1 axle-and a flexible WebEeng'agingsurfac'e sleeve rotatable about said curved axle, means *suppor'tingthe opposite end portions of said axle for movements of the axle and the roll thereon about a straight transverse axis common to said supporting'mearis'at the opposite end portions er the axle, whereby the position of the roll maybe adjusted about said "straight .axistochan'ge the length'of thepath of travel between said guide elements of one portion of the web relative to "aflaterally difierent portion of the web, and powermeans having drive connection WithSsa'id rotatable-sleeve offthe roll for rotating the sleeve about the curved axis'of said curvedaxle in eachposition to which the roll may be move'dabout said transverse straight axis.

4. In a web-handling apparatus having a pairof spaced and parallel guide elements and web 'drawingmeans for drawing the web in guided'engagement with said guide elements, the combination'therewith .of a longitudinally curved roll disposed transversely of the web between said guide elements, sa'id'roll having a longitudinally curved axle and a flexibleweb-engaging surface sleeve rotatable about'said' curved axle, meansincluding end clamps supporting the opposite ends of said axle for movements of the axle and roll about a straight transverse axis which is common to said supporting means at the opposite ends of-the axle thereby to adjust said curved axis to any of various positions angula'rly around said straight axis,

a motor supported in driving relation to said flexible surface sleeve of the roll, and a drive connection between said motor and said surface sleeve and operative for rotating said surface sleeve about said curved axis in each angular position to which said curved axis may be adjusted around said straight axis.

5. In a web-handling apparatus having a pair of spaced and parallel guide elements and web-drawing means for drawing the web in guided engagement with said guide elements, the combination therewith of a longitudinally curved roll disposed transversely of the web between said guide elements, said roll having a longitudinally curved axle and a flexible web-engaging surface sleeve rotatable about said curved axle, end clamps for said axle having provision for adjusting the curved axis of the axle about a second axis into any of a variety of planes and adapted to maintain the axle against rotation when its curved axis is in any one of said planes, a motor supported in driving relation to said flexible surface sleeve of the roll, a drive connection between said motor and said surface sleeve whereby the web-engaging surface sleeve may be rotated by said motor, and means-for varying the torque applied to said surface sleeve by said drive connection.

6. In a web-handling apparatus having a pair of spaced and parallel guide elements and web-drawing means for drawing the web in guided engagement with said guide elements, the combination therewith of a longitudinally curved roll disposed transversely of the web between said guide elements, said roll having a longitudinally curved axle and a flexible web-engaging surface sleeve rotatable about said curved axle, means adjustably supporting the opposite ends of the roll axle whereby the said flexible surface sleeve may be shifted about a second axis between different web-engaging positions thereby to change the length of the path of travel between said guide elements of one portion of the web relative to a laterally different portion of the web, power means for driving the surface sleeve in each of its said web-engaging positions, and means operative at saidpower means for varying the torque with which said surface sleeve is driven thereby to materially reduce the tension-increasing effect of the surface sleeve on the web in the said different web-engaging positions of the surface sleeve.

7. In a web-handling apparatus having a pair of spaced and parallel guide elements and web-drawing means for drawing the web in guided engagement with said guide elements, the combination therewith of a longitudinally curved roll disposed transversely of the web between said guide elements, said roll having a longitudinally curved axle and a flexible web-engaging surface sleeve rotatable about said curved axle, means adjustably supporting the opposite ends of the roll axle for movements of the axle and roll about a straight transverse axis common to said supporting means at the opposite ends of the axle whereby the said flexible surface sleeve may be shifted about said straight axis between different webengaging positions thereby to change the length of the path of travel of a laterally different portion of the web, power means for driving the surface sleeve in each of its said web-engaging positions, thereby to materially reduce the tension-increasing effect on the web due to the engagement of the surface sleeve therewith.

8. Apparatus for acting on a travelling web during the progress of the web to a processing mechanism which mechanism positively grips the edges of the web to advance the edges of the web at a predetermined rate of travel, said apparatus comprising a roll rotatably mounted I in position to be engaged and rotated by the web as the web approaches the processing mechanism, means for shifting the position of the roll to change the length of the path of travel of one edge portion of the web relative to the length of the path of travel of a laterally different portion of the web, the web having a predetermined amount of tension between said roll and said processing mechanism when the roll is in a neutral position, and the resistance of said shifted roll to rotation by the web being such that if the roll were to be rotated bythe web the web tension would be increased between said apparatus and said processing mechanism substantially above said predetermined amount of tension and would be concentrated at portions of the web which have increased length of paths of travel and, in combination therewith, adjustable means for applying driving torque to the roll in its said shifted positions in selective amounts to maintain the tension in the web between said apparatus and said processing mechanism substantially the same when the roll is in its neutral position and when it is in said shifted position.

9. Apparatus for acting on a travelling web during the progress of the web to a processing mechanism which mechanism positively grips the edges of the web to advance the edges of the web at a predetermined rate of travel, said apparatus comprising a longitudinally curved roll having a longitudinally curved axle and a flexible surface sleeve rotatable about the axis of the curved axle,

'said curved roll being mounted in position to be engaged and its surface sleeve rotated by the web as the web approaches the processing mechanism, means adjustably supporting the ends of said curved shaft whereby the roll may be set in a neutral position in which all portions across the width of the web have substantially equal paths of travel in reaching the processing mechanism and in which the web between the roll and the processing mechanism has a predetermined amount of tension therein, and may be set in any of various other positions in each of which the central portion of the web will have a different length of path of travel than the length of the paths of travel of the edge portions of the web and in each of which the web between the roll and the processing mechanism will have increased tension therein above said predetermined amount of tension and will have the increased tension concentrated at the portion or portions of the web having the longer paths of travel, and, in combination therewith, adjustable means for applying driving torque to the roll in selective amounts to maintain the tension in the web between the roll and the processing mechanism substantially the same when the roll is in its neutral position and when it is in any of its said various other positions.

10. Apparatus for correcting a displaced condition of the transverse elements of a travelling woven web, com prising a pair of spaced and parallel guide elements, means beyond the guide elements in the direction of travel of the web for drawing the web in guided engagement with the guide elements on a course leading to said drawing means with a predetermined amount of tension in the portion of the web which is entering the drawing means, a roll rotatably mounted between said guide elements in position to be engaged and rotated by the travelling web, means for shifting said roll between a neutral position and selective correcting positions, all portions across the width of the web having equal length of paths of travel between the guide elements when the roll is in its neutral position but different portions across the width of the web having unequal lengths of paths of travel between the guide elements when the roll is shifted to any of its said correcting positions, and the tension in said portion of the web which is entering the drawing means being increased above said predetermined amount of tension and concentrated at the portion or portions of the web having the longer paths of travel when said roll is shifted to any of its said correcting portions, and, in combination therewith, adjustable means for driving said roll with an applied torque conduciveto maintenance of average tension across the width of said portion of the web which is entering the drawing .means substantially the same when the roll is in its neutral position and when it is in any of its said correcting positions. 1 1. Apparatus for handling woven webs, comprisingin combination, a pair of spaced-apart and parallel guide elements, means for drawing a woven web in guided engagement with said guide elements, a web engaging roll rotatably mounted between said guide elements and disposed transversely of the web, said roll having a neutral position in which all portions across the width of the web have equal length of paths of travel between said guide elements, means for adjusting the roll between its said neutral position and positions in which an edge portion of the web has a length of path of travel between said guide elements substantially different from the length of the path of travel of a laterally different portion of the web, and means for controlling the increase of tension on 10 the web due to the presence of said roll, comprising a motor having drive connection to the roll in all of its said positions, and means for selectively varying the driving torque applied to the roll by said motor.

References Cited in the file of this patent UNITED STATES PATENTS 1,595,544 Farrell Aug. 10, 1926 1,776,382 Farrell Sept. 23, 1930 1,853,975 Isherwood Apr. 12, 1932 2,220,760 Gates Nov. 5, 1940 2,496,312 Robertson Feb. 7, 1950 

